EP0790727A2 - Procédé de démodulation d'un signal reçu - Google Patents

Procédé de démodulation d'un signal reçu Download PDF

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Publication number
EP0790727A2
EP0790727A2 EP97100483A EP97100483A EP0790727A2 EP 0790727 A2 EP0790727 A2 EP 0790727A2 EP 97100483 A EP97100483 A EP 97100483A EP 97100483 A EP97100483 A EP 97100483A EP 0790727 A2 EP0790727 A2 EP 0790727A2
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EP
European Patent Office
Prior art keywords
coefficients
frequency offset
formula
partial sequences
symbols
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP97100483A
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German (de)
English (en)
Other versions
EP0790727A3 (fr
Inventor
Uwe Dettmar
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ascom Intermediate AG
Original Assignee
Ascom Tech AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ascom Tech AG filed Critical Ascom Tech AG
Publication of EP0790727A2 publication Critical patent/EP0790727A2/fr
Publication of EP0790727A3 publication Critical patent/EP0790727A3/fr
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/0212—Channel estimation of impulse response
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L25/03012—Arrangements for removing intersymbol interference operating in the time domain
    • H04L25/03114—Arrangements for removing intersymbol interference operating in the time domain non-adaptive, i.e. not adjustable, manually adjustable, or adjustable only during the reception of special signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L7/00—Arrangements for synchronising receiver with transmitter
    • H04L7/04—Speed or phase control by synchronisation signals
    • H04L7/041—Speed or phase control by synchronisation signals using special codes as synchronising signal
    • H04L7/042—Detectors therefor, e.g. correlators, state machines

Definitions

  • the invention relates to a method for demodulating a received signal which, in addition to the data to be transmitted, contains a predetermined synchronization sequence.
  • the invention further relates to an arrangement for carrying out the method.
  • the object of the invention is to provide a method of the type mentioned at the outset, which is not limited to a specific signal format and which avoids the known nonlinearities which are problematic in the case of faults.
  • a significant advantage of the invention is that it is also possible to work with synchronization sequences that are not ideal in their correlation properties.
  • the synchronization sequence is often specified by a technical standard, which must be taken into account when implementing a signal receiver. It should also be noted that a synchronization sequence as a whole can have ideal autocorrelation properties, but this does not apply to shorter sections (partial sequences) of such an ideal sequence.
  • the frequency offset ⁇ is preferably calculated in accordance with equation VI in the sense of a simplification.
  • the computational effort is less than with the estimate according to Formula I.
  • a significant deterioration in performance compared to the more complex estimate does not have to be accepted if the autocorrelation properties of the partial sequences do not deviate too much from the ideal case.
  • the partial sequences can be defined or tapped in the sense of ideal autocorrelation properties. The estimate according to formula VI (or XI) will then be completely satisfactory.
  • the channel impulse response h can also be determined with minimal additional computational effort. According to the invention, equations VII-VIII are used for this.
  • a simplification which is suitable for partial sequences with good (especially ideal) correlation properties, results from the channel estimation according to formula IX (or XII).
  • the partial sequences preferably have a length in the range of several ten symbols (for example 50):
  • the corresponding observation windows can in principle adjoin one another, but are preferably at a distance which is, for example, at least as large as the length of a partial sequence. Each the larger the observation window, the less the disturbing influence of the noise.
  • a memory is also used for the values of the matrix ⁇ which can be calculated in advance and a computing circuit for evaluating equation II.
  • the appropriate formulas can simply be programmed to carry out the preferred methods described.
  • the received symbols d i are detected, for example, with an equalizer 15 or another detection circuit known per se.
  • the actual data is given by a so-called synchronization sequence. It is a given sequence of symbols, which the recipient knows in advance.
  • the synchronization sequence has a length of 400 symbols, for example.
  • two sub-sequences of the synchronization sequence are scanned with a switch 1, for example.
  • the partial sequences define corresponding observation windows. You cannot overlap.
  • the symbols of the synchronization sequence have the index i, which runs, for example, from 1-400 (total length of the synchronization sequence).
  • the first partial sequence begins at a predetermined index i 0 and runs until i 0 + N-1.
  • the second partial sequence runs analogously from i 1 to i 1 + N-1. N therefore denotes the length of the two partial sequences or observation windows.
  • the scanned symbols d i are placed in a buffer memory 2.
  • a read-only memory 3 contains the previously known symbol values u * i0 + 1 to u * i0 + N of the first partial sequence and the values u * i1 + 1 to u * i1 + N of the second.
  • Formula V is now evaluated with arithmetic circuit 4.
  • M denotes the number of (considered) coefficients of the channel impulse response. The result is two vectors ⁇ * [0] and ⁇ * [1].
  • ⁇ * [0] denotes the values belonging to the first sampling window [i 0 ] and ⁇ * [1] the values belonging to the second sampling window [i 1 ].
  • the star stands for complex conjugate.
  • the coefficients h [ 0 ] and h [ 1 ] of the channel shock response are calculated in the two observation windows.
  • the values ⁇ * [ 0 ] and ⁇ * [ 1 ] are stored in a buffer memory 5.
  • a read-only memory 6 contains the matrix values ⁇ t, k according to equation III.
  • the symbols u i of the partial sequences are known in advance, so that the matrix values ⁇ t, k mentioned can be calculated when the receiver circuit is implemented.
  • the coefficient vector h can be calculated for both observation windows from the inverted matrix ⁇ -1 * according to equation II.
  • Equation I was thus evaluated with the arithmetic circuit 12.
  • the coefficients h [ 1 ] are delayed by an M times the symbol duration T with a delay element 13.
  • the coefficient vector h is determined on the basis of the estimated frequency offset in accordance with equations VII and VIII.
  • the correlation coefficients R k can also be determined according to formula (X) in order to calculate the phase shift ⁇ and the coefficients of the impulse response h according to formulas (XI) and (XII).
  • the arithmetic circuit 14 can be dispensed with if it is sufficient to know the relative size of the coefficients of the channel impulse response.
  • the equalizer 15 can, for example, include a corresponding constant phase shift of the symbols.
  • the buffer store 2 can be designed, for example, as a simple shift register. This means that the received symbols d i are - in the sense of a correlation - pushed over the stored partial sequences.
  • the method according to the invention is advantageously carried out by a special DSP (digital signal processor).
  • DSP digital signal processor
  • the invention has created a method for estimating the frequency offset and optionally the channel impulse response, which is essentially independent of the signal format.
  • the area of application of this method is correspondingly broad.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Synchronisation In Digital Transmission Systems (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
EP97100483A 1996-02-19 1997-01-15 Procédé de démodulation d'un signal reçu Withdrawn EP0790727A3 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
CH43096 1996-02-19
CH430/96 1996-02-19
CH43096 1996-02-19

Publications (2)

Publication Number Publication Date
EP0790727A2 true EP0790727A2 (fr) 1997-08-20
EP0790727A3 EP0790727A3 (fr) 1999-06-23

Family

ID=4186847

Family Applications (1)

Application Number Title Priority Date Filing Date
EP97100483A Withdrawn EP0790727A3 (fr) 1996-02-19 1997-01-15 Procédé de démodulation d'un signal reçu

Country Status (2)

Country Link
US (1) US5995572A (fr)
EP (1) EP0790727A3 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2782215A1 (fr) * 1998-08-10 2000-02-11 Alsthom Cge Alcatel Intervalle de temps comprenant des symboles de reference utilise dans un reseau de transmission de type cdma
WO2001017185A1 (fr) 1999-09-01 2001-03-08 Telefonaktiebolaget Lm Ericsson (Publ) Estimation, dans un recepteur en rateau, de la vitesse de changement de voie

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB0001491D0 (en) * 2000-01-24 2000-03-15 Univ Manchester Pre-processor
US7079599B2 (en) * 2001-02-28 2006-07-18 Broadcom Corporation Multi-mode quadrature amplitude modulation receiver for high rate wireless personal area networks
GB0124952D0 (en) * 2001-10-17 2001-12-05 Nokia Corp A receiver and a receiving method
KR100534592B1 (ko) * 2002-06-20 2005-12-07 한국전자통신연구원 디지털 통신 시스템의 수신 장치 및 그 방법
DE102004059958B4 (de) * 2004-12-13 2007-10-04 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Vorrichtung und Verfahren zum Bestimmen eines Korrelationswertes
US7804763B2 (en) * 2005-04-04 2010-09-28 Current Technologies, Llc Power line communication device and method
US7671701B2 (en) * 2006-06-09 2010-03-02 Current Technologies, Llc Method and device for providing broadband over power line communications
US8188855B2 (en) 2008-11-06 2012-05-29 Current Technologies International Gmbh System, device and method for communicating over power lines
US20100111199A1 (en) * 2008-11-06 2010-05-06 Manu Sharma Device and Method for Communicating over Power Lines
US8279058B2 (en) 2008-11-06 2012-10-02 Current Technologies International Gmbh System, device and method for communicating over power lines
US10957445B2 (en) 2017-10-05 2021-03-23 Hill-Rom Services, Inc. Caregiver and staff information system

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4577328A (en) * 1982-10-30 1986-03-18 Nec Corporation Method and circuit for detecting a training signal
US4674103A (en) * 1985-08-28 1987-06-16 International Business Machines Corp. Method and arrangement for detecting the presence of a training signal in a modem receiver
US5422917A (en) * 1993-01-04 1995-06-06 Novatel Communications Ltd. Frequency offset estimation using the phase rotation of channel estimates
US5440589A (en) * 1993-02-18 1995-08-08 Fujitsu Ltd. Frequency offset dealing modulator and demodulator apparatus
US5471501A (en) * 1991-06-27 1995-11-28 Hughes Aircraft Company Enhanced digital communications receiver using channel impulse estimates

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5233632A (en) * 1991-05-10 1993-08-03 Motorola, Inc. Communication system receiver apparatus and method for fast carrier acquisition

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4577328A (en) * 1982-10-30 1986-03-18 Nec Corporation Method and circuit for detecting a training signal
US4674103A (en) * 1985-08-28 1987-06-16 International Business Machines Corp. Method and arrangement for detecting the presence of a training signal in a modem receiver
US5471501A (en) * 1991-06-27 1995-11-28 Hughes Aircraft Company Enhanced digital communications receiver using channel impulse estimates
US5422917A (en) * 1993-01-04 1995-06-06 Novatel Communications Ltd. Frequency offset estimation using the phase rotation of channel estimates
US5440589A (en) * 1993-02-18 1995-08-08 Fujitsu Ltd. Frequency offset dealing modulator and demodulator apparatus

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
DETTMAR U: "Combined channel estimation and frequency correction for packet oriented mobile communication systems" SEVENTH IEEE INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS. PIMRC'96 (CAT. NO.96TH8240), PROCEEDINGS OF PIMRC '96 - 7TH INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR, AND MOBILE COMMUNICATIONS, TAIPEI, TAIWAN, 15-18 OCT. 1, Seiten 334-338 vol.2, XP002100822 ISBN 0-7803-3692-5, 1996, New York, NY, USA, IEEE, USA *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2782215A1 (fr) * 1998-08-10 2000-02-11 Alsthom Cge Alcatel Intervalle de temps comprenant des symboles de reference utilise dans un reseau de transmission de type cdma
EP0980152A1 (fr) * 1998-08-10 2000-02-16 Alcatel Intervalle de temps comprenant des symboles de référence utilisé dans un réseau de transmission de type CDMA
WO2001017185A1 (fr) 1999-09-01 2001-03-08 Telefonaktiebolaget Lm Ericsson (Publ) Estimation, dans un recepteur en rateau, de la vitesse de changement de voie
US6850505B1 (en) 1999-09-01 2005-02-01 Telefonaktiebolaget L M Ericsson (Publ) Method and apparatus for Doppler frequency estimation

Also Published As

Publication number Publication date
US5995572A (en) 1999-11-30
EP0790727A3 (fr) 1999-06-23

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